Thermostat.



W. H. KALLENBACH.

THERMOSTAT.

APPLICATION FILED JUNE 10. 1914.

Patented Mar. 20, 1917.

WALTER H. KALLENBACH, 0F BOSTON, MASSACHUSETTS.

THERMOSTAT.

Application filed June 10, 1914.

To all whom it may concern: I

Be it known that I, VJALTER H. KALLEN- men, a citizen of the United States, residing at Boston, in the county of Suffolk and Fitate of Massachusetts, have invented a new and useful Improvement in Thermostats, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to thermostats of that class commonly used to actuate a fire alarm system in which an expansion memher is operated to close an electric circuit to operate the alarm when the temperature in the room or s aace where the thermostat is located. is'raised to a predetermined de- 5 The main object of the invention is to pro vide a thermostat of the above described class which is of cheap and du able construction and which is sure, etiicient and positive in its operation.

Another ob ect of the invention is to provide a thermostat having two expansion members, without increasing the size of the thermostat, thereby making its operation doubly certain.

A further object of the invention is to provide expansion members of such form that when they are caused to expand by the rising of the temperature in the room, the circuit is closed by a sliding contact so that any dust, dirt or corrosion which accumulates at the point of contact will be removed by the glancing or sliding movement of the expansion member thereby assuring a free passage for the electriccurrent.

Another object of the invention is to pro vide an expansion member having a wide range of movement when expanded by heat in order to make the device sensitive and to allow the air gaps between the expansion members and the terminals to be so wide that a collection of moisture on the expansion member and terminals will not result in a short circuiting of the current.

Another object of the invention is to provide a thermostat having its terminal plates entirely surrounded by a molded insulating material in order that short circuiting, due to the accumulation of moisture, may be effectively guarded against.

Specification of Letters Patent.

Patented Mar. 20, 1917.

Serial No. 844,355.

ing the preferred form of my invention, Figure 1 is a plan view of a thermostat constructed in accordance therewith; Fig. 2 is a central vertical sectional view on line 22 in Fig. 1; Fig. 3 is a central vertical sectional view on line 33 in Fig. 1; Fig. l is a view in perspective of a terminal plate and Fig. 5 is a side elevation of said terminal plate.

In the illustrated embodiment of my invention is shown a thermostat comprising a base 6 provided with two terminal plates 8 each having an expansion member 10 adapted to engage the other terminal plate to close an alarm circuit when the temperature rises to a predetermined degree.

The base (3 is composed of non-conducting material. such for instance as vulcanized rubber and the terminal plates 8 are embedded therein with the exception of certain portions which project therefrom. Each terminal plate 8 consists of a body portion having a lateral portion 12 extending obliquely therefrom and lying in the same plane. The inner end of the body portion and the end of the lateral extension are turned upwardly to form posts 1% and 16 respectively. The outer end of the body portion is provided with a hole 18 to receive a screw 20 for the purpose of securing thereto one wire of the electric circuit in which the thermostat is arranged. lVhen the terminal plates are embedded in the base the only portions which project are the ends to which the circuit wires are attached and the posts. 1-;-land 16.. The remaining portions of the terminalplates are entirely surrounded by and inclosed in the base, that is, in a non-conducting material.

In making the base I prefer to use a nonconducting material which can be molded around the terminal plates in the desired form while in a plastic condition and compressed and then hardened either by vulcani nation or in any other way. Constructing the base in this manner reduces the cost of manufacture and secures efliciency by insulating all the parts of the terminal plates except those portions which are attached to the circuit wires, contact members and expansion members. 7

To the post 14 of each terminal plate is secured by a screw 22 an expansion member 10 which may be made of any suitable material or of two metals having different c0- efficients of expansion. Each of these members consists of two U-shaped portions in a substantially perpendicular relation to each other Fig. 1) and this form of the expansion members constitutes the most important feature of my invention, and its ad vantages will be pointed out hereinafter.

In the post 16 of each plate is arranged a screw 2st which operates as a contact member for the expansion member upon the other plate and by turning the screws the air gaps between the expansion members and the contact members may be increased or diminished and the temperature at which the thermostat will operate to sound an alarm thereby regulated.

The arrangement 01" the expansion and contact members .is illustrated in place in Fig. 1, the terminal plates being shown in dotted outlines, the end 26 of each expansion member engaging the contact screw 2% and thereby closing the circuit between the two terminal plates.

F or the purpose of securing the thermostat in place on the ceiling or wall of a room, the base is provided with a central boss or hub 28 having a hole 30 to receive a nail or screw and this hub is preferably formed ot the same non-conducting material as the base. Any other suitable means may, however, be employed for securing the device in place. The base of the thermostat, it will be noticed, is convex which prevents the accumulation of moisture thereon and any short circuiting at that point.

A cover 32 may be provided for inclosing the operative parts and is preferably pierced by holes Set to permit the air to have free circulation through the cover and in contact with the expansion members.

Vhen in use a thermostat is arranged in an electric circuit the wires 36 and 38 of the circuit being connected one to each terminal plate 8 by means of the screws 90. In this connection it will be observed that the ends 40 of the terminal plates are turned upwardly as shown in Fig. 2 which is downwardly when the thermostat is secured to a ceiling and the circuit wires 36 and 38 are held in the angles thereby formed by the screws 20. This construction has several advantages in that the circuit wires are not cut by the heads or" the screws when they are turned down too hard and if the thermostat becomes detached from the ceiling by reason of vibration or otherwise, it is supported by the circuit wires and remains operative. The circuit is normally open and remains open until one or both of the expansion members engages the contact member or members 24: when the circuit is closed and the current thereupon operates an alarm, sprinkler or other mechanism which is also in the circuit.

The operation of the device is as follows: As the temperature in the room or space where the thermostat is located goes up the expansion member is caused to expand and the end 26 approaches the contact member 2ft. It the thermostat be adjusted to 155 degrees then at that temperature the free end of the expansion member will engage the contact member and close the circuit which immediately actuates the alarm arranged within the clectric circuit at some distant point.

As hereinbefore stated, the form of the expansion member or members is one of the most important features of my invention. I have found from a long series of experiments that this form of expansion member has so 'cral advantages. In the first place its form enables me to employ two expan sion members and two contact members without lIlCl'OtlSlllg the size of the thermostat and when two sets of expansion and contact members are used, it constitutes what might be termed a double apparatus so that it for any reason one expansion member should fail. to work, there is another to close the circuit and actuate the alarm. In the second place I secure an ex pansion member which is more sensitive and in which the arc traveled by the end of the expansion member as the temperature rises is greater than that of any other form of expansion member known to me. This en ables the thermostat to be adjusted with a larger air gap between the contact member and the end of the expansion member so that short circuiting by reason of moisture accumulating either on the contact member or expansion member or both is rendered, for all practical purposes, impossible. This also enables the thermostat to be adjusted to a wider range of tennperature and more accurately to any given temperature. In the third place the expansion of the expansion member causes the end 26 to be moved in a direction perpendicular to the axis of the contact member so that after a contact is made between the contact member and the end of the expansion member, any further increase in temperature causes the end of the expansion member to slide upon the end of the contact member. This sliding contact will remove any dirt or corrosion which may have accumulated on the end of the expansion member and will ultimately make a good contact even if the first contact is inoperative.

It will be noticed in Fig. 1 of the drawings the expansion member, as it leaves the post H, is bent slightly to one side. I have found by constructing it in this manner rather than having it lead from the post ll practically in the same plane, results in a wider range of movement of the end 26 of the expansion member.

Although I have shown my thermostat as comprising two sets of expansion and contact members in what may be termed a double construction it may be used with but a single set if preferred. lVhile the double set gives additional security so far as positive operation of the device is concerned, yet is not absolutely necessary to use two sets so far as the purposes of my invention are concerned.

My thermostathas the advantage of having comparatively few parts and of being extremely simple both in construction and operation so that it may be made at a very low cost; Owing to the construction of the base having terminals embedded therein, and in view of the wide gaps between the expansion and contact members, the gathering of moisture upon the thermostat cannot operate to cause a short circuiting and a premature sounding of the alarm.

It is to be understood that my invention may be embodied in other forms of construction than that herein shown and described and I desire to claim it broadly except where specifically limited in the following claims.

1V hat I claim is 1. A thermostat comprising two terminals, an adjustable contact member mounted on one of said terminals and an expansion member mounted on the other of said terminals for closing a circuit through said terminals when a predetermined temperature is attained; said expansion member being composed of two U-shaped portions substantially in a right-angled relation to each other.

2. A thermostat comprising two terminal plates and an expansion member secured to one of said plates and adapted to engage the other of said plates when expanded by heat, said expansion member having two U-shaped portions arranged substantially in rightangled relation to each other.

3. A thermostat comprising two terminals and an expansion member mounted on each of said terminals and adapted to engage the other of said terminals when a predetermined ten'iperature is attained; each of said expansion members comprising two U- shaped portions in a substantially rightangled relation to each other.

i. A thermostat comprising two terminals, an adjustable contact member on each of said terminals and an expansion member on each of said terminals, each of said expansion members being adapted to engage the said contact member on the other terminal. to close a circuit through said ter minals when expanded by heat; each of said expansion members comprising two U- shaped portions in a substantially rightangled relation to each other.

5. A thermostat comprising two terminal plates and two expansion members, each of said expansion members being secured at one end to one of said plates and adapted when expanded by heat, to engage at the other end the other of said plates, each of said expansion members having two U-shaped portions arranged substantially in right-angled relation to each other.

6. A thermostat comprising two terminal plates, each of said terminal plates having two posts, a contact member mounted on one of said posts of each terminal plate and an expansion member mounted on the other post of each plate, each of said expansion members being so arranged that the tree cud oi said member engages the cont: rt member on the other of said terminal plates when the temperature reaches a pre-dctermined degree; each of said expansion members being made up of two J-shaped portions arranged substantially in right-angled relation to each other.

7. A thermostat comprising a base of nonconducting material, two terminal plates each having two posts and with the exception of said two posts being entirely embedded in, and surrounded by said base, two expansion members secured to said plates, one to each plate, and so arranged that the free end 01- each of said expansion members engages one of the posts on the other terminal plate to close a circuit when the temperature reaches a predetermined degree.

8. A thermostat comprising a base of nonconducting material, two terminal plates entirely embedded therein except one end and one post of each plate, a contact member on the post of one of said plates, and an expansion member secured to the post of the other of said plates for closing the circuit when the temperature reaches a predetermined degree; said expansion member comprising two U-shaped portions arranged substantially in right-angled relation to each other.

9. A thermostat comprising two terminal plates, each of said plates having two posts, an adjustable contact member mounted on one of said posts on each plate and an expansion member mounted on the other post of each plate, said expansion members being so arranged that when expanded by the raising of the temperature to a predetermined degree each expansion member engages the contact member in the other terminal to close the circuit.

10. A thermostat comprising two terminal plates and an expansion member mounted on each plate, each of said expansion members being adapted, when expanded by heat, to engage the other of said plates.

11. A thermostat comprising two terminal plates and an expansion member mounted on each of said plates, each of said expansion members being adapted, when expanded by heat, to engage a contact portion on the other of said plates for closing a circuit.

12. A thermostat comprising two terminal plates and an expansion member mounted on each plate, one of said expansion members being made up of two U-shaped portions arranged substantially in right-angled relation-to each other and both of said expansion members being adapted, when expanded by heat, to engage the other of said plates in order to close a circuit.

13. A thermostat for actuating a fire alarm comprising two terminal plates and an expansion member mounted on each plate and adapted, when expanded by heat, to cause said alarm to sound, each of said expansion members being made up of two U- shaped portions arranged substantially in right-angled relation to each other.

ll. A thermostat con'iprising two terminal plates and an expansion. member mounted on each plate and adapted, when expanded by heat, to engage the other of said plates; said plates being arranged in opposition to each other with the expansion members extending in opposite directions thereby permitting the thermostat to be assembled within a small area.

15. A thermostat comprising two terminal plates, each having an expansion member mounted on one end and a contact member on the other end, each of said expansion members being adapted, when expanded by heat, to engage the contact member on the other of said plates to close a circuit and said plates being arranged in opposition to each other with the expansion men bers extending in opposite directions thereby per- Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). C. 

